Files
CMake/Modules/CheckVariableExists.cmake
Matthew Woehlke 2edf0fc6d7 Modules: Use new keyword-dispatched try_compile signature
Modify most of the modules that ship with CMake to use the new
try_compile / try_run signatures added by commit aa9220d3a0
(try_compile: Add keyword-dispatched signature, 2022-09-02). This
improves debugging by each invocation using its own directory so that
the results of multiple invocations can be retained.

This does not cover any invocations which provide an entire project, as
that flavor of try_compile has not yet been updated.
2022-09-14 07:52:16 -04:00

90 lines
2.9 KiB
CMake

# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#[=======================================================================[.rst:
CheckVariableExists
-------------------
Check if the variable exists.
.. command:: CHECK_VARIABLE_EXISTS
.. code-block:: cmake
CHECK_VARIABLE_EXISTS(VAR VARIABLE)
::
VAR - the name of the variable
VARIABLE - variable to store the result
Will be created as an internal cache variable.
This macro is only for ``C`` variables.
The following variables may be set before calling this macro to modify
the way the check is run:
``CMAKE_REQUIRED_FLAGS``
string of compile command line flags.
``CMAKE_REQUIRED_DEFINITIONS``
list of macros to define (-DFOO=bar).
``CMAKE_REQUIRED_LINK_OPTIONS``
.. versionadded:: 3.14
list of options to pass to link command.
``CMAKE_REQUIRED_LIBRARIES``
list of libraries to link.
``CMAKE_REQUIRED_QUIET``
.. versionadded:: 3.1
execute quietly without messages.
#]=======================================================================]
include_guard(GLOBAL)
macro(CHECK_VARIABLE_EXISTS VAR VARIABLE)
if(NOT DEFINED "${VARIABLE}")
set(MACRO_CHECK_VARIABLE_DEFINITIONS
"-DCHECK_VARIABLE_EXISTS=${VAR} ${CMAKE_REQUIRED_FLAGS}")
if(NOT CMAKE_REQUIRED_QUIET)
message(CHECK_START "Looking for ${VAR}")
endif()
if(CMAKE_REQUIRED_LINK_OPTIONS)
set(CHECK_VARIABLE_EXISTS_ADD_LINK_OPTIONS
LINK_OPTIONS ${CMAKE_REQUIRED_LINK_OPTIONS})
else()
set(CHECK_VARIABLE_EXISTS_ADD_LINK_OPTIONS)
endif()
if(CMAKE_REQUIRED_LIBRARIES)
set(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES
LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
else()
set(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES)
endif()
try_compile(${VARIABLE}
SOURCES ${CMAKE_ROOT}/Modules/CheckVariableExists.c
COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
${CHECK_VARIABLE_EXISTS_ADD_LINK_OPTIONS}
${CHECK_VARIABLE_EXISTS_ADD_LIBRARIES}
CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_VARIABLE_DEFINITIONS}
OUTPUT_VARIABLE OUTPUT)
if(${VARIABLE})
set(${VARIABLE} 1 CACHE INTERNAL "Have variable ${VAR}")
if(NOT CMAKE_REQUIRED_QUIET)
message(CHECK_PASS "found")
endif()
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
"Determining if the variable ${VAR} exists passed with the following output:\n"
"${OUTPUT}\n\n")
else()
set(${VARIABLE} "" CACHE INTERNAL "Have variable ${VAR}")
if(NOT CMAKE_REQUIRED_QUIET)
message(CHECK_FAIL "not found")
endif()
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
"Determining if the variable ${VAR} exists failed with the following output:\n"
"${OUTPUT}\n\n")
endif()
endif()
endmacro()